SOM does not use a common MCMC. It is hard to get its explicit expression and what it find is not the expectation on a certain distribution but several configurations with small $\chi^2$ by short MCMC chains. Throwing some configurations with big $\chi^2$ and take average of $A$ obtained from reminding configurations.
SOMdoes not use a common MCMC. It is hard to get its explicit expression and what it find is not the expectation on a certain distribution but several configurations with small